One of the most serious problems a payment system can have is to double charge a customer. When we design the payment system, it is important to guarantee that the payment system executes a payment order exactly-once. At the first glance, exactly-once delivery seems very hard to tackle, but if we divide the problem into two parts, it is much easier to solve. Mathematically, an operation is executed exactly-once if:
why do we put the key in HTTP header not request body? I'm not familiar with payment.
stripe recommends V4 UUIDs to be used as a best practice